This disclosure generally relates to systems and methods for improving the accuracy of large guns.
Conventional guns (such as the M198 or M777 155-mm howitzer or large naval guns) rely on chemical propellants which limit their muzzle energy, range, and down-range accuracy. Multiple factors (such as powder temperature) may cause the muzzle velocity of a conventional projectile to vary a few percent from nominal. In some guns a change of just 1° C. in the chemical propellant can cause a 1.5 m/sec change in muzzle velocity, where every 1 m/sec variation from nominal muzzle velocity in a conventional projectile means the ordinance will be off target 30-40 m down range. For example, a 3% deviation from a nominal muzzle velocity of 800 m/sec is 24 m/sec, which could cause the projectile to be delivered almost 1 km away from its desired target. Conventional guns also suffer from barrel wear as they fire more and more rounds. Barrel wear may cause the projectile to leave the gun slightly off center, resulting in a potentially unpredictable trajectory, thereby further reducing down-range accuracy. Additionally, current weapons systems have reached a limit for muzzle velocity with existing explosives.
Coil guns are electromagnetic guns that use the Lorentz force to accelerate a projectile with a conducting armature. For high-speed applications, induction coil guns use magnetic coupling to drive current in the armature without direct electrical contact between the barrel and projectile. Some induction coil guns consist of short-length, solenoidal electromagnets that are stacked end to end. The coils are energized sequentially to create a wave of electromagnetic energy moving from breech to muzzle in order to accelerate the armature. Active tracking of the projectile location during launch provides precise feedback to control when the coils will be triggered to create the electromagnetic wave that propels the projectile.
Existing solutions of bringing electromagnetically propelled weaponry to the battlefield require complete re-design and re-build of existing systems. There is presently no electromagnetic solution known to the authors that can be installed or mounted on existing weapons platforms without major modifications. There is also no known solution to controlling muzzle velocity of conventional guns that use chemical propellant. Guided munitions can be used to control accuracy, but they are very expensive compared to unguided munitions.
It would be desirable to provide a system that can actively control the muzzle velocity of a projectile as it leaves a gun by detecting the velocity of the projectile as it leaves the gun and then adjust its velocity to a target velocity. Preferably this system would be easily retrofit onto existing guns so that minimal or no re-design of the gun or projectile would be necessary.